Sewing machine feed mechanism



Jan. 24, 1939. R K HOHMANN 2,144,802

sEwiNG MACHINE FEED MECHANISM Original Filed Dad. 29, 1936 3Sheets-Sheet l J Ill B; v K .NVENTOR ATTORNEY- Jan. 24, 1939. R. KHOHMANN I W SEWING MACHINE FEED MECHANISM Original Filed Dec. 29, 1956 3Sheets-Sheet 2 ATTORNEY Jan. 24, 1939. R. HOHMANN 2,144,802

SEWING MACHINE FEED MECH'ANISM Original Filed Dec. 29, 1936 5Sheets-Sheet 3 INVENTOR A'i'T'ORNEY Patented Jan. 24, 1939 "UNITEDSTATES PATENT OFFICE 2,144,802 SEWING MACHINE FEED MECHANISM Richard K.Hohmann, meme, N. Y. Original application December 29, 1938, Serial No.

Divided and this application April 3,

1937, Serial No. 134,729

7 Claims.

stitching operations in which no automatic work feed is needed ordesired.

The said means comprise two cams, so mounted on a rotatable shaft of thesewing machine, such as the underbed hook driving shaft or upper needlebar shaft, that one of the cams may rotate with the shaft at all times,while the second cam may or may not rotate with the shaft accordingly asoperation f the feed mechanism is or is not desired.

A further specific object of the invention is to include in the feedmechanism, novel and effective provisions for varying the stitch length,

not onlyin the normal stitching, but also in the backstitching,operation. My work feed mechanism improvements were primarily devisedfor use, and may be used with especial advantage, in portable domesticsewing machines, but may also be used with advantage in other sewingmachines.

The various features ofnovelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, its advantages, and specific objects attained with its use,

had to the accompanying reference should 'be drawings and descriptivematter inwhich I have illustrated and described a preferred embodimentof the present invention.

or the drawings:

Fig. 1 is an elevation of the machine partly broken away and in section;

Fig.2 is an inverted plan view of the underbed mechanism of'the machine;

Fig. 3 is a rear end elevation of a lower portion of the sewing machinewith a detachable drive mechanism cover plate removed;

Pg. 4 is a vertical section on the line H of Fig. 2;

Fig. 4A is a partial vertical section on the line lA-lA of Fig. 4;

Fig. 5 is a vertical section on the line 5-5 of Fig. 2;

Fig. 6 is a section taken similarly to Fig. 5,-but showing parts indifferent relative positions;

Fig. 7 is, apartial section on the line 1-1 of Fig. 2;

Fig. 8 is a section taken similarly'to Fig. 7, but showing Parts indifl'erent relative positions:

Fig. 91s a Fig. 8. a

As shown in the drawings, the sewing machine mechanism is partlyreceived in, and is wholly supported by a base member A. The latter isin the form of a flat cast metal box having a removable top plate partB, forming the cloth or bedplatc of the machine. .-The hollow standardC, arm C, and head (3, andother frame parts C C, C", and C', as shownare all parts of a one partial section on the line 9-8 of piece metalframe casting, to which the bed plate B is secured as by screws. Theparts C C C and C' are all within the round the lower portion of thestandard C. The parts C and C are parallel, spaced apart foot or legportions of the framework, which bear directly against the bottom wallof the base member A, and are detac bly connected thereto, by screws C".

The lower portion of the hollow standard C is enlarged at its rear toprovide a housing for the upper portion of a driving element, shown as agrooved pulley D having an enlarged hub portion the bobbin windingoperahand wheel for manual ad justments oi the mechanism. The saidhousing is closed at its rear sideby a removable are shaped cover partC', extending over the exposed hub portion D, and having horizontallyextending foot portions detachably secured to the rear end wall of thebase A. The pulley D is mounted on a crank shaft E, and driven by anelectric motor F, shown as located wholly within the base A beneath thebed plate B and the armature shaft of which may carry a pulley driving.Pu'lley D through a belt F. To accommodate its bobbin winding use, thepulley D is preferably a socalled loo se" pulley, operatively secured tothe crank shaft E only when clamped to the latter by an externalclamping nut D threaded on the outer end portion E "bf the crank shaftE, and engaging the pulley D through a friction washer D splined on theshaft portion E.

The crank shaft E is journalled in frame bearings and extends across theinterior of the ho].- low standard, C, with the cloth plate level. Tofacilitate its assembly and re-assembly, the rear or outer end portion Eof the crank shaft is separable from the remainder or body portion ofthe crank shaft and normally connected to the latter by a key E Therotation of the crank shaft E gives rotative movements to the needle barshaft 0, which passes horizontally through the hollow arm C, through acrank or-connecting rodor lever G. The latter has a lower hub portion Gsurrounding the crank pin portion E of the crank shaft E, and isprovided at its upper end with a transverse pin G receivedin a radialslot a in a crank its axis preferably below base member A, and', coveredby the plate 13, which is notched to surfurther referred to herein.

In the form of construction shown in Figs. 1, 2, and 3, the rotativemovements of the crank shaft gives corresponding movements to the mainunderbed shaft H, through toothed gears E. and H carried by the crankshaft and underbed shaft respectively, which advantageously and asshown, are spiral gears, with a one to one gear ratio. The shaft H isjournalled in aligned bearings in the frame C and 0, and in a bearingblock C secured to the underside of the frame portion C.

has two arms I and I,*one generally parallel with, and the othertransverse to, the shaft H,

which are adjustably clamped against the underside of the frame part 0*by clamping bolts I and I". The clamping bolt 1 for the arm I extendingtransversely to the shaft H passes through a hole in a bushing 1 whichmay be protated for adjustment purpose, in the hole in the arm Ireceiving it, and has its-hole receiving the clamping bolt 1 eccentricwith respect to theperiphery of the bushing. In consequence, byloosening the clamping bolts, and angula'rly adjusting the bushing I,the hook shaft may be bodily adjusted toward the axis of the shaft H, asrequired to take up for wear of the gearsH" and I. The bolt 1'' passesthrough an opening in the-arm I elongated in the direction of thelatter, so that when the clamping bolts are eased off, the hook shaftmaybe bodily adjusted in the direction of the length of the shaft H tothereby properly position the hook relative to the path of movement ofthe .needle. To permit of easy lubrication of the'two bearings in thesupport I for the hook shaft, one above and the other below the gear I,the hookshaft is formed with an axial oil channel 1 closed at its lowerend, but open to the bobbin chamber of the hook at its upper end, andformed with a lateral oil outlet 1 for each bearing. Those bearings maythus be readily lubricated, when the bobbin is removed from the hook, bydropping oil into the bobbin chamber.

In front of the gear H, the shaft H carries two work feed cams JA andJB. The cam JA is rigidly, though preferably adjustably, secured to theshaft H, but the cam JB, while normally in the fixed relation to theshaft H shown in Fig. '7, may be adjusted as and for the purposehereinafter described, into the position shown in the Fig. 8 in which itdoes not share in the rotative movement of the shaft H. In the normalrunning position illustrated in Fig. '7, the rotation of the cams JA andJB give feed movements to a feed dog J through mechanism comprising afeed bar J, to which the feed dog J is rigidly secured. The feed bar J,which is gen-, erally horizontal, is formed at its rear end with upperand lower prongs J, which straddle a stationary guide pin C", forming aguide for the rear end of the feed bar in the longitudinal the upperfront side inclined upwardly from movements of the latter, and forming apivotfor the feed bar in its oscillatory up and down movements.' It isgiven its up and down oscillatory movements, in the normal stitchingoperation,. ,by the cam .113, against whichthe underside of the front bya spring .1.

end portion of the bar is normallyheld The feed bar .1 is given itslongitudinal movements by a 'fork lever J, formed with upper and lowerprongs J at its front end, which straddle the cam'JA. At its rear end,the fork lever is pivotally connected to the feed bar J by means of apivot pin J carried by depending ear extensions J" from the lower prongJ of the feed bar J'.

The oscillatory up and down movements given to the prongs J of the forklever J by the cam JA normally give that lever, and thereby the feed dogJ reciprocatory movements in the generally horizontal direction of thefeed bar J, as a result of the interaction of a block J carried by apivot pin J', projecting "laterally from the fork lever J with a guidemember K, formed with a guide slot K receiving the block J". The memberK is pivotally mounted on a horizontal stub shaft or post 0 parallel tothe shaft H and anchored in the frame part C The part K has an armconnected by a pivot K to one end of a link K, having its other endpivotally connected by pivotpin K to an arm K carried by a rock shaft K.The latter is beneath the bedplate B, and parallel to the shaft H, andis joumalled in bearingscarried by the front frame part C at itsunderside. The rearend of the shaft K extends into the housing chamberfor the pulley D, and has an operating arm K link connected to it, asshown in Figs. 1 and 3. The arm K projects through a slot C formed inportion of the housing wall, andelongated to permit of a substantialangular adjustment of the shaft K by manipulation of the outer end ofthe arm i The angular adjustment which may thus be given to the shaft Kissufiicient to adjust \the angle of the inclination'me'mber K betweenpositions respectively shown in Figs. 5 and 6. As shown in Fig. 5, theslot K in the member K is the horizontal and for wardly from thevertical plane through the axis of the shaft H. In the position shown inFig. 6,

theslot K is inclined upwardly from the hori- .carried by the forklever, then moves down in the slot K, and gives the feed dog J arearward movement and thus effects the normal feed movement of the workaway from the operator, who is in front of the machine, as the latterappears in-Flg. 1. With the member K adjusted into the position shown inFig. 6, the feeding movement of the feed dog is toward the operator.

When the arm K is adjusted to make the direction of the slot K vertical,the feed dog will have no feeding movement. The extent of feedingmovement, and consequently the length of each stitch formed, willprogressively diminish to zero as the member K is progressively adjusted75 from either of its positions shown in Figs.- 9 and 10, to theintermediate no feed position in which the slot K is vertical. The armor finger K thus forms a readily accessible and easily operableactuating member of mechanism by which the direction of feed may bereversed, and by which the length of the stitch formed with eitherdirection of feed may be varied as desired. As shown, the wall of thepulley housing in which the slot C is formed, is provided with scalemarks C, which in conjunction with the index formed by the arm K",furnish an easily read indication of the direction of feed and length ofstitch formed with any existing adjustment of the arm K".

The cam JB is adjustable longitudinally of the shaft H. To this endthecam JB has a hub extension provided with circumferential collars JB' andJB spaced apart to provide a circumferential groove JB entered by a pinL carried by a lever L. The latter has one end pivoted at L to thesupporting framework of the mechanism, and has its other end pivotallyconnected to one end of a link L which is beneath the clothplate, andhas its other end pivotally connected to an operating lever L The latteris pivotally connected to the framework by a, pivoted pin L and extendsup through a slot formed in the clothplate B adjacent the standard C. Byoscillating the lever L, the cam member JB, under certain conditions,can thus be adjusted longitudinally of the shaft H, between its normaloperative position shown in Fig. 7, and its inoperative position showninFig. 8.

In its operati"e position, the cam JB is connected to the shaft H torotate with the latter, by means of a pinJB parallel to, and laterallydisplaced from the shaft H, and anchored in the cam JB and projectingfrom the face of the latter adjacent the cam JA. In the position of camJB shown in Fig. 7, the pin JB extends into a socket formed for thepurpose in the cam JA, which is rigidly secured to the shaft H. When thecam JB is displaced from the cam JA as shown in Fig. 8, the pin 313* iscompletely withdrawn from its socket in the cam-JA, and the cam JB isout of driving engagement with the shaft H.

Means are provided which, prevent the cam JB from being adjusted fromthe position shown in Fig. 7 into that shown in Fig. 8, except when theangular position of the cam JB is such that the feed bar J the cam JB,so that the feed dog J is then wholly below the top surface of theclothplate or bed of the machine. In consequence, with the cam JB in theposition shown in Fig. 8, the rotation of the shaft H through cam JAgives movement to the feed dog J in the general horizontal direction ofthe feed bar J, but such feed dog movements will be idle, because thefeed dog is below its work engaging level. The said means compelling thefeed dog to be below the work engaging level, when the cam JB is in theposition of Fig. 8, comprises a part M carried by the frame part 0 atthe underside of the latter. The latter is at the right hand side of thecam JB when the latter is in the position shown in that Fig. 7. Thecollar JB is of sufiicient radial extent to engage the part M, andprevent movement of cam JB into the position shown in Fig. 8, exceptwhen the angular position of the cam JB is such as to bring afiattenededge portion J12, of the collar J13 into parallelism with the the cam JBinto the manual adjustment by the operator.

bears against a low portion of underside of the member ures 8 and 9.

The purpose of holding the feed dog-J below its working level, effectedby the adjustment of position shown in Fig. 8, is to facilitate.operations, such as darning operations. in which the work is preferablynot subject to automatic feed action, but is free for When such anoperation is being carried out, the usual pres- M, as shown by Fi surefoot N is ordinarily removed temporarily.

With the presser foot removed, as the needle starts up, and the needlethread is slackened, so

that in normal operation it forms a loop in .po-

sition for engagement 'by the thread engaging point of the hook I",

there would be occasional failure of the needle thread to form a loop inposition for engagement by the hook, but for a special corrective device0 (Fig. 4), which I provide. The device 0 is there is a tendency for thework to lift with the needle. In consequence,

a thread engaging finger or loop controller secured to' the frameopposite part C The device O, by engaging the portionof the needlethread adjacent, but above the eye in the needle OB, and at the side ofthe needle remote from the hook I, forces the thread to move through theeye of the needle as the latter starts its upstroke, and thus insuresthe formation of the proper thread loop at the hook side of the needlefor engagement by the hook point, notwithstanding the tendency of thework to lift with the needle, when not prevented by the presser footeiiect. The arrangement and operative action of the thread controller 0need not be further illustrated and described herein, as it forms nopart of the invention claimed herein, and is more fully disclosed in myprior application for patent, Serial Number 118,038, filed December 29,1936, of which the present application is a divisicn. Said priorapplication contains claims 'on various novel features including thesaid controller O invented by me, and disclosed, but not claimed herein.

While novel features of my improved sewing machine may be used withadvantage in sewing machines which are not primarily intended fordomestic use, and which are not portable, it will be apparent to 'thoseskilled in the art that my improvements are especially well adapted foruse,

and to contribute to the operative characteristics desirable, in smalllight weight portable sewing machines intended primarily for domesticuse. In particular, it is to be here noted that the provisions made forrendering the feed mechanism inoperative during a stitching operation inwhich the normal feed connection is undesirable, and the provisions madefor reversing the direction of the feed and for varying the length ofthe stitches formed, are desirable, not only because of their relativesimplicity and effectiveness, but also because the entire feedingmechanism may be compactly and conveniently arranged in the availableunderbed space of the machine except for the operating members L and K",which project from the sewing machine structure at points convenientlylocated for engagement by the operator.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form of my invention now known to me,it will be apparent to those skilled in the art that changes may be madein the apparatus disclosed, without departing from the spirit of myinvention as set forth in the appended claims, and 7 that certainfeatures of my invention may sometimes be used with advantage, without acorrespending use of other features.

Havingnow described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In a sewing machine comprising a workbed with a feed dog opening, thecombination with a feed dog, of a rotatable cam and means through whichthe rotation of said cam gives said feed dog horizontal to and fromovements, a second rotatable cam and means by which the rotation ofsaid second cam gives said feeddog movements upward to and downward froma position in which it extends through said opening, and meansalternately operable to simultaneously rotate both cams or to rotate thefirst mentioned cam withoutrotating the second mentioned cam.

2. In-a sewing machine comprising a workbed with a feed dog opening, thecombination with a feed dog, of a rotatable cam beneath said bed andmeans through which the rotation of said cam gives said feed doghorizontal to and fro movements, a second rotatable cam beneath said bedand means by which the rotation of said second cam gives said feed dogmovements upward to and downward from a position in which it extendsthrough said opening, and means alternately operable to simultaneouslyrotate both cams or to rotate the first mentioned cam without rotatingthe second mentioned cm.

3. In a sewing machine comprising a supporting structure including aworkbed formed with a feed dog opening, the combination of a horizontalrotatable shaft beneath said bed, a cam mounted on said shaft, 2. feeddog, means through which said cam moves said'feed dog up into and downfrom a position in which it projects upwardly through said opening whensaid cam is rotated, means including an, operating part projecting fromsaid structure for engagement by the hand of the operator for releasablyconnecting said shaft and cam for rotation of the latter by the shaft,and means for maintaining said cam, when disconnected from saidshaft,-in position to hold the feed dog below its above mentionedposition. 4. In a sewing machine comprising a workbed formed with a feeddog opening, the combination of a horizontalrotatable shaft beneath saidbed, a cam secured to said shaft, a second cam mounted on said shaft andaxially adjustable relative to the latter, means coupling said secondcam to said shaft for rotation with the latter in one position of saidcam axially of said shaft, means for holding said second cam, when in asecond position axially of said shaft. against ro tation with said shaftand in a predetermined angular position, a feed dog, means through whichthe rotation of the first mentioned cam gives horizontal to and fromovements to said feed dog, and means-actuated by the rotation of saidsecond cam to move said feed dog up to and down from a position in whichit projects through said opening. and holding said feed dog out of itssaid position .when said second cam is in it said second axial position.5. In a rotary hook sewing machine comprising a workbed, the combinationwith a rotating horizontal underbed hook driving shaft, of an underbedfeed bar support, laterally displaced from said shaft, a feed barmovable up and down "and horizontally to and fro in a directiontransverse to said shaft, a lever pivotally connected to said feed barand cam means carried by said shaft giving said feed bar up and downmovements and giving oscillatory movements tosaid lever, a memberangularly adjustable about an axis beneath said bed and parallel to saidshaft, and formed with a guideway extending transversely to said axis,said lever having a guide portion engaging the said guidewaywhereby'when said member is angularly adjusted to one side or the otherof an intermediate position, the oscillatory movements given said leverby said second cam means gives said feed bar horizontal to and fromovements in timed relation with its up and down movements and of amagnitude which varies with the angular displacement of said member fromsaid intermediate position, and the ing a workbed, the combination witha rotating horizontal underbed hook driving shaft, of an underbed feedbar support displaced from said shaft, a feed bar having one end inengagement with said support and movable relative thereto, angularly upand down, and horizontally to and fro in a direction transverse to saidshaft, a cam carried by said shaft giving said bar its angular up anddown movements, a second cam carried by said shaft, a lever pivotallyconnected to said feed bar and engaging, and given angular up and downmovements by, said second cam, a member angularly adjustable about anaxis beneath said bed and parallel to said shaft, and formed with aguideway extending transversely to said axis, said lever having a guideportion engaging the said guideway, whereby when said member isangularly adjusted to one side or the other of an intermediate.position, the up and down movements given said lever by said second camgives said feed bar horizontal to and fro movements in timed relationwith its up and down movements and of a magnitude which varies with theangular displacement of said member. from said intermediate position,and the phase relation of which to the up and down movements of the feedbar is varied approximately 180 by the angular adjustment of'said memberfrom one side to the other of said intermediate position, and meansincluding a manually operable part projecting from said structure forangularly adjusting said member about said axis.

I. In a sewing machine comprising a supporting structure including aworkbed formed with a feed dog opening, the combination of a horizontalrotatable shaft beneath said bed, a cam mounted on said shaft, a feeddog, means through which said cam moves said feed dog up into and downfrom a pomtion in which it projects upwardly through said opening whensaid cam is rotated,

said shaft and cam for rotation of the latter by the shaft.

, RICHARD K. HOHMANN.

